>>536529894
It's intimidating to look at all the bones but here is a nice shortcut for you. What matters the most is the mouth corners, pick a base expression to mold your desired expression from then move the mouth corner bones up or down, give it a try! I've attached a picture of the bones so you can see what I did.
>>536530091
That looks so goofy, I don't personally like to go too wild with it. I prefer to keep them as grounded as possible, start small until I feel it's in a good spot.
>>536530269
I've got a very good one for you here, be careful about opening the jaw with rotation. Try using lip movement animations to do the heavy lifting for you then adjust it.